I haven't seen any data. Scala has been around for a while, which means more time to spend on optimization, so it's probably faster at this point. Because of garbage collection on JVM, Swift has the potential to be more performant though.
Unless you are trying to build some really high performance shit, what really matters is developer productivity, which is abysmal for server-side Swift right now. Getting better every day though.
Unless you are trying to build some really high performance shit, what really matters is developer productivity, which is abysmal for server-side Swift right now. Getting better every day though.
Source: built and deployed a service in Swift